Manufacture and use of PCBs, DDT and other persistent chlorinated hydrocarbons have ceased in the United States. However, very large quantities of these toxic and potentially carcinogenic compounds remain dispersed in the environment where their distribution and fate are imperfectly characterized. Moreover, additional PCBs and other organochlorines continue to be added to the environment, particularly to natural waters where they contaminate the sediments and can be taken up by fish and then by humans. To investigate current sources of PCBs, DDT-derived compounds, and chlordane to the natural waters adjacent to New York City, analyses of dated sediment core sections and sewage-related samples will be performed. Data from sewage sludge samples will be used to characterize local sources of chlorinated organic hydrocarbons. Contaminant levels in sediments will be interpreted on the basis of sewage sludge data and known industrial sources. Temporal trends in contaminant levels throughout the NY-NJ harbor complex will be determined through the analysis of dated sediment cores. Comparisons of PCB compositions in archived and recent sediment core samples will be used to elucidate the rates and pathways of in situ reductive dechlorination, a process that reduces the carcinogenic toxicity of PCBs and forms the basis of several new remediation technologies. The levels of persistent chlorinated hydrocarbons in sediments and their temporal trends are an excellent indicator of the levels and trends in fish. Since fish consumption is a major pathway of human exposure, the project relates to a significant health concern. Extracts of representative contaminated sediments will be supplied for projects 6, 7, and 8 which address direct links between contaminant exposure and human breast cancer.